What Happens When an Oracle Cloud Infrastructure Compute Instance Fails Health Checks

Instances Failing Health Checks Behind Public Load Balancer

Question

Your application front end consists of several Oracle Cloud Infrastructure compute instances behind a public load balancer.

You have configured the load balancer to perform health checks on these instances.

What will happen if an instance fails to pass the configured health checks?

Answers

Explanations

Click on the arrows to vote for the correct answer

A. B. C. D.

B.

Sure, I'd be happy to help explain what happens if an instance fails to pass the health checks configured on a public load balancer in Oracle Cloud Infrastructure.

Answer B is correct: the load balancer will stop sending traffic to the instance that failed the health check.

Here's a more detailed explanation:

A public load balancer in Oracle Cloud Infrastructure (OCI) is a service that distributes incoming traffic across multiple compute instances in a backend set. When an incoming request is received, the load balancer selects a healthy instance from the backend set to handle the request.

To determine which instances are healthy, the load balancer performs health checks on each instance at regular intervals. A health check involves sending a request to a specified endpoint on the instance and checking the response. If the instance responds with a 200-level HTTP status code within a specified timeout period, the health check is considered successful and the instance is marked as healthy. If the instance fails to respond or responds with a non-200-level status code, the health check is considered a failure and the instance is marked as unhealthy.

When an instance fails a health check, the load balancer will stop sending traffic to that instance. The load balancer will continue to periodically check the failed instance's health and will resume sending traffic to the instance if it passes the health check again.

Note that the load balancer does not terminate or replace unhealthy instances automatically. It is up to the user to configure automated remediation actions, such as terminating and replacing instances using OCI's instance pool feature or a custom script.